Open Source, Delay Tolerant Network, Internet of Things

Knowledge Without Boundary

Saturday, December 27, 2014

The related email data that need to be synchronized located in offline server computer, online server computer and infomediary device. The database synchronization performed by comparing the email data reside in server computer and infomediary device. Database synchronization application on server computer will check if the email data path on the server computer and email data path on infomediary device availability. When infomediary device connected in the server computer local network, the networking path of the email data on infomediary device will be discovered by database synchronization application. Database synchronization application will start comparing the email data between server computer and infomediary device. If there is no change of email data between server computer and infomediary device, the synchronization process is finished. When there is new email data found, the database synchronization application will start retrieve the new email data from infomediary device and transfer new email data to the infomediary device. Figure 5.3 shows the flowchart of the database synchronization.

Roundcubemail version 0.7.2 served as Mail Client application for an offline mail client and an online mail client. Mail Client is a mail user agent (MUA). It is a web application used to access and manage the email. The application file extracted into respective location and the folder renamed into “pemail”. In this thesis work, the location is:

“C:\PEmailOffline\UniServer\www\pemail.”

Mail Client installation performed by entering the URL: http://localhost/pemail/installer into the web browser. The configuration for both offline mail client and online mail client should be the same for the database synchronization purpose where the product_name, syslog_id and the database name is pemail, the database server is localhost and the database username and password configured accordingly for administrator access. IMAP Settings for offline mail client configured where the IP address of the offline server computer which is 192.168.1.7 was used as a default host address. This IP address is accessible only in LAN. IMAP common port which is 143 was set for default port with username domain is “pemail.suroot.com” which is used for email address. SMTP settings for offline mail client configured where the IP address of the offline server computer also used for the SMTP Server address. SMTP common port is 25. The current IMAP username and password was used for SMTP authentication. This option can be configured under SMTP settings.

SMTP settings for online mail client configured where the domain name of the online server computer which is “pemail.suroot.com” was used for the SMTP Server address. This domain is accessible through internet. SMTP common port is 25. The current IMAP username and password also used for SMTP authentication and configured under SMTP settings.

When the configuration is completely configured, this mail client configuration is saved through “create config” button where it will create two configuration files which are “main.inc.php” and “db.inc.php”. This configuration files transferred into a mail client application folder such as:

“C:\PEmailOffline\UniServer\www\pemail\config”

The configuration can be tested through “Test config” button. The configuration is correct and working when everything was remark with “OK”. Then the “installer” folder can be removed from mail client application folder.

The files “.htaccess” in temp, logs and config folder which located in mail client folder “C:\PEmailOffline\UniServer\www\pemail” need to be configured to enable access of this Mail Client. This can be done by commenting next two lines in “. htaccess” files as shown in Table 5.8 by adding “#”.

New user registration page only required on online mail server to avoid database synchronization conflict between offline mail system and online mail system. Configuration for online mail client is the same as for the offline mail client except that online mail client includes the “new user registration” page. Plugins “roundcube-0.7.2-bundle-v.1.0” required for enabling “new user registration” page. The plugins can be found at http://code.google.com/p/myroundcube/downloads/list. The required plugin files which are bundle register, taskbar and captcha plugins were transferred into email plugins folder which is located at “C:\PEmailOnline\UniServer\www\pemail\plugins”. New plugins were enabled in an active plugins configuration file at “C:\PEmailOnline\UniServer\www\pemail\config” by editing “/config/main.inc.php” file and append new plugin names into configuration directive as shown in Table 5.9.

Then, taskbar plugin “/plugins/taskbar/config.inc.php.dist” file can be activated by renaming into “/plugins/taskbar/config.inc.php”, captcha plugin “/plugins/captcha/config.inc.php.dist” file can be activated by renaming into “/plugins/captcha/config.inc.php” and register plugin “/plugins/register/config.inc.php.dist” file can be activated by renaming into “/plugins/register/config.inc.php”. HMailServer SQL database driver name to be used in registering new users is “'hmail_sql_db_4402” and need to be set by editing file “/plugins/register/config.inc.php” as shown in Table 5.10.

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Tuesday, December 23, 2014

Offline mail server and online mail server
should use the same configuration. This is to enable mail data synchronization
where both mail servers should share the same content and configuration for
data synchronization purposes. HMailServer
version 4.4.4 being used as mail server application. HMailServer installed to respective location as “Full installation”
with Server and Administrative tool component included. A database server is an
external database which is a new hMailServer
database created on MySQL Server and running on Uniserver. The database server address is “localhost” and TCP Port
is 3306. The database name for this offline email system is “pemail” and should
be the same for both offline server computer and online server computer. HMailServer security password configured
accordingly. The created database location is:

The domain name
for this offline email system is pemail.suroot.com which can be configured
accordingly at hMailServer
Administrator welcome pages. A public host name also configured as
“mail.pemail.suroot.com” under Settings -> Protocols -> SMTP, Delivery of
e-mail tab. SMTP relayer setting depends on ISP either port 25 is open or not.
If port 25 is open, a free SMTP relayer can be used such as
“mail.hmailserver.com 25”. Since 03 November 2008, TM Streamyx was blocking
outgoing port 25 [28]. TM had suggested using
the configuration for SMTP relayer as “smtp-proxy.tm.net.my”.

The port can be
tested by running the command: telnet smtp-proxy.tm.net.my 25 and the result should
a success connection as in Figure 5.2. The offline mail server is not needed to
use suggested SMTP relayer setting, but it is recommended to use the same
configuration since whenever the offline mail server connected to the internet,
the offline email system can communicate directly without the need of infomediary
device.

Monday, December 22, 2014

The Uniform Server setup for online web server is the same as for
offline server. The IP address used is 192.168.1.7. The difference is that the
online server is connected to the internet. The Internet Service Provider being
used in this research is TM Streamyx Dynamic 1 MBps. This ISP provides an
internet with dynamic IP address connection. The external IP address will
change periodically depending on the ISP. This leads to an access problem to
existing setup to act as a server. To solve that problem, DtDNS service is
used. DtDNS is a complete provider of DNS hosting and DNS management services
with a focus on dynamic DNS and dynamic IP address management. There is a free
domain name provided and tracking software to automatically update IP address
as it changes. This free service enables a dynamic IP address to host a service
just as it had a static IP address. The DtDNS service hostname details for this
offline email system configured where the hostname is pemail and domain is
suroot.com.

Cron is used to
integrate DtDNS with Uniform Server.
Cron originated from a UNIX environment. It is a job scheduler allowing scripts
to be run automatically at a certain time or date. Cron has been integrated
into Uniform Server 7.1.4. The script
has been pre-configured to run the three scripts which are Drupal Cron, Moodle
Cron and DtDNS automatic IP updater. Only script for DtDNS automatic IP updater
used for this offline email system. Cron automatic update default period is
every ten minutes. DtDNS automatic IP updater has been pre-configured, but it
is disabled by default on Uniserver. To
enable DtDNS automatic IP updater, Cron configuration file in
C:\PEmailOffline\UniServer\unicon\main\run_cron.php edited by changing lines in
the section list of scripts to be run as shown in Table 5.5 (A). Then those
lines uncomment as shown in Table 5.5 (B).

DtDNS account details where the
hostname is pemail.suroot.com and password configured in a Cron script
configuration file located in:

“C:\PEmailOnline\UniServer\plugins\dtdns_updater\dtdns.ini”

Uniserver
uses binary code 1 which means perform the function while 0 means ignore and do
nothing. Default value "7" is a total of 1+2+4 which will run the
Apache, MySQL and Index page processes. Cron Binary code is
"16".Total binary code value for Apache, MySQL and Cron is 19. Figure
5.1 shows the binary codes have been assigned.

To enable automatic
Cron on Uniserver, file in “C:\PEmailOffline\UniServer\unicon\main\includes\config.inc.php”
edited as shown in Table 5.6. This binary code value will enable the Apache,
MySQL, Index page processes and Cron run when the Uniserver program started.

Apache, MySQL
and Cron need to be configured to start up all at once. Cron can be configured
to run automatically when the servers are started by editing file in
C:\PEmailOnline\UniServer\unicon\tray_menu\UniTray1.ini. Under “LEFT MENU”
there are lines to control Server Start and Stop. Programs or batch files that
run either of the control scripts start_servers.php or stop_servers.php must
include a single binary coded parameter. If this parameter is missing defaults
value 7 are used. A parameter overrides any default settings this allows
independent control of a particular function. Then, default binary code should
be changed from 7 to 19 for these lines "%PHP%\php.exe";
Parameters: " -n %ServerConMain%\start_servers.php 19"; as
per Table 5.7 below:

Sunday, December 21, 2014

Web server application running on the
server computer to deliver webmail page access to the client. Web server
application for this system is Uniserver
7.1.4. Web server application file extracted to respective location which
is C:\PEmailOffline\UniServer for offline environment server computer. Starting
Uniserver will open a Server
Administrator page in a default Web Browser. The Server Administrator page only
accessible by the server computer admin. Admin of the server computer used this
page to configure the username and password for the admin panel configuration,
private server configuration and private secure server configuration (SSL) and MySQL
server configuration. MySQL is a relational database management system (RDBMS)
used by the web server application. Files C:\PEmailOffline\UniServer\www\.htaccess
edited with text editor and next four lines commented by adding “#” to allow
external access as per Table 5.4 below:

This will disable
server security limitation access from localhost only and enable access using the
server IP address. The PHP value for maximum message size located in “. htaccess”
file in "...UniServer\www\pemail" and “php.ini” file in
"...UniServer\usr\local\php" also configured to upload maximum file
size is 10MB, post maximum size is 50MB and memory limit is 64MB. This value is
to give a size limit of attachment file.

This offline
email system uses MIME standards and do not specify any file size limits for
maximum upload size to be allowed [25]. Limits for maximum upload size can be
configured in web server setting file “php.ini”, where the maximum attachment
size is 2147483647 MB which is a maximum value for a 32-bit signed integer
supported by a SQL database. The maximum message size is unlimited by setting
the value to zero. The maximum disk space that the account may use is limited
to the server computer hard disk storage available space. If the hard disk is
full, the limit is reached and the account will not be able to receive any more
email. If a maximum message size is specified, the mail server will reject
messages larger than that size. It is recommended to set a maximum message size
limit to prevent the server from any types of attack. As an example, attackers
could send a big size message and fills the server hard disk which will cause a
problem to the server computer.

This offline
email system maximum message size is set to 50MB. The mail server will reject
messages larger than this size. Email content size is small and usually 1MB or
less. This offline email system maximum message size is set to 10MB. Limiting
maximum attachment size default value 10MB is acceptable to ensure the mail
server network performance is not dropping when multiple users uploading a very
big file at the same time to the mail server. Limiting the size of email
attachments to 10MB is also a safe setting for the maximum size of an email
since other email services commonly used 10MB as a maximum size of an email
attachment. If the maximum size of an email attachment is 30MB or greater than
10MB and this offline email system is successfully send the email to the
receiver, there is no guarantee that the receiver can receive the email since
there is a different maximum size limitation of email attachment on every email
service. Gmail limiting the size of email attachments to 25MB with no specified
limit to the number of attachment as long the total size is 25MB [26]. Yahoo Mail allows
user to upload up to 50 files to an email message as long as the total message
size remains under 25MB [27].

Every email
account has total allocated maximum size storage. If an email is sent to this
account when the quota has been used, the mail server will deliver a
notification to the sender containing the information that the quota for the
recipient had been reached. After that, the email message will be dropped. Each
email in this offline email system allocated size is set to 250MB.